Arrhenius Equation Calculator

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Choose which variable to solve for. The inputs that are needed will update automatically.
Chemists most often use the per-mole form with the gas constant R. Physicists and some computational chemists use the per-molecule form with the Boltzmann constant kB.
The Arrhenius frequency factor (collision frequency), in the same units as k. Typical values range from 10^10 to 10^15 s^-1 for unimolecular reactions.
The minimum energy (in kJ/mol) that reacting molecules must have for the reaction to proceed. Typical values range from 40 to 200 kJ/mol.
kJ/mol
Absolute temperature in Kelvin. To convert from Celsius, add 273.15. Room temperature is approximately 298 K.
K
Rate constant kModerate activation energy
17,217.487576

Reaction rate constant at the given temperature

Activation energy Ea50kJ/mol
ln(k)9.7537
Half-life (first-order)0s
50 kJ/mol
Very fast<40Moderate40-80High barrier80-120Very slow120+

Rate constant k = 1.722 x 10^4 at 298 K

  • At 298 K, the rate constant is 1.722 x 10^4 (in whatever units A was given).
  • Assuming first-order kinetics, the half-life at this temperature is about 0.0000 seconds.
  • Raising the temperature increases k exponentially - a rule of thumb is that a 10 K rise roughly doubles the rate for Ea near 50 kJ/mol.

Next stepTo see how k changes with temperature, switch to the "Rate at new temperature" mode or inspect the Arrhenius plot.

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